Method for producing polyamide fiber having improved silky feel and lustre

ABSTRACT

POLYAMIDE FIBER HAVING IMPROVED SILKY LUSTRE AND SILKY TOUCH IS PRODUCED BY MELT-SPINNING MODIFIED POLYAMIDE PELLETS OBTAINED BY DISPERSING FINE PARTICLES OF POLYALKYLENE ETHER INTO POLYAMIDE, CONTINUOUSLY DRAWING THE MELT SPUN FILAMENTS UNTIL THE BIREFRINGENCE OF SAID FILAMENT REACHES A SPECIFIC PRE-SELECTED POINT, TREATING THE DRAWN YARN WITH A SOLVENT FOR POLYALKYLENE ETHER AND RECOVERING THE SAME.

May 22, 1973 TETSUYA KATO ETAL 3,734,986

METHOD FOR PRODUCING POLYAMIDE FIBER HAVING IMPROVED SILKY FEEL ANDLUSTRE Filed July 31, 1970 2 Shutl-Sheet 1 50- 40- 3 v 5 9 30 g x s 2 G)V 5 IO- 0 l l I I T a, Millimol Alkylene Oxide per gram Polyomide J Z'INVENTORS.

TETSUYA KATO TOSHIAKI HIDAKA BY CHIKATSU OKAGAWA ATTORNEYS.

May 22, 1973 TETSUYA KATO ET AL 3,734,986

METHOD FOR PRODUCING POLYAMIDE FIBER HAVING IMPROVED SILKY FEEL ANDLUSTRE Filed July 51, 1970 2 Sheets-Sheet 2 REFLECTANCE MEASUREMENT INPLANE COINCIDENT WITH YARN AXIS Fig. 3

REFLECTANCE MEASUREMENT AS YARN AXIS IS ROTATED IN PLANE COINCIDENT WITHYARN AXIS INVENTORS. TETSUYA KATO TOSHIAKI HIDAKA BY CHIKATSU OKAGAWAATTORNEYS United States Patent 3,734,986 METHOD FOR PRODUCING POLYAMIDEFIBER HAVING IMPROVED SILKY FEEL AND LUSTRE Tetsuya Kato, Nagoya,Toshiaki Hidaka, Nishikasugaigun, and Chikatsu Okagawa, Nagoya, Japan,assignors to Toray Industries, Inc., Tokyo, Japan Filed July 31, 1970,Ser. No. 60,029 Int. Cl. B29d 27/00; D01d 5/08, 5/12 U.S. Cl. 264-49Claims ABSTRACT OF THE DISCLOSURE Polyamide fiber having improved silkylustre and silky touch is produced by melt-spinning modified polyamidepellets obtained by dispersing fine particles of polyalkylene ether intopolyamide, continuously drawing the melt spun filaments until thebirefringence of said filament reaches a specific pro-selected point,treating the drawn yarn with a solvent for polyalkylene ether andrecovering the same.

The present invention relates to a method for producing a polyamidefiber having improved silky lustre and silky touch, and moreparticularly, to a method for producing such an improved polyamide fiberby meltspinning a polyamide fiber having polyalkylene ether incorporatedtherein.

Polyamide fiber has been used for textile products such as are used inclothing because it has excellent strength, high anti-abrasion,excellent dyeability, and high washand wearability. (It should be notedhere that fiber is used to denote both filamentary fiber andmulti-filament yarn.)

However, the conventional polyamide fiber has a waxy touch andappearance which are inherent disadvantages of the synthetic fiber, andwhich therefore restrict the applications thereof.

Numerous attempts have been made to produce polyamide fibers having thedesirable mild lustre and touch of the natural fiber most preferred inthese respects, i.e., silk, by eliminating the waxy touch and appearanceof the synthetic fiber.

In one example of such attempts, the cross sectional surface of thefiber is changed from circular into multilobal form. This eliminates thewaxy touch of the synthetic fiber but the surface of the fiber glistensand the lustre of the synthetic fiber is completely different from thatof silk.

The inventors of the present invention have found that the preferredproperties of silk, in particular, silky lustre and touch can beobtained in a polyamide fiber by providing in the polyamide fiber voidsof the appropriate size and volume and by appropriately making thesurface of the fiber coarse.

As a method for producing voids in such fibers, there is a prior artmethod in which organic material and high polymer material are blendedand the mixture is meltspun; thereafter the filament is treated with asolvent, to remove soluble inorganic material from the high polymermaterial. However, in this method, the inorganic material tends to clogthe filter of the spinning machine and the melt-spinning operation istherefore very difficult.

There is another conventional method for producing voids in fiberaccording to which two kinds of polymers are blended, and the blendedmixture is melt-spun; thereafter one of the polymers is extracted with asolvent. In one example of this method, as described in thespecification of Japanese patent publication No. 25 169/ 1965, polyamideand polystyrene are blended. However, when this method is employed, themutual solubility of the blended polymers is poor, and, in addition,fine particles of polymers cannot be easily mixed. Thereforemelt-spinnability is poor, and, in addition to the above, voids ofappropriate size cannot be obtained; thus the silky lustre cannot beeasily attained. Furthermore, another draw back of this method is thatit is necessary to use an organic solvent, which is very difiicult tohandle, for producing voids by extracting one of the polymers.

On the other hand, in US. Pats. Nos. 3,329,557 and 3,475,898 a method isdisclosed in which fibers of excellent antistatic property can beobtained by blending therein polyalkylene ether. At the same time, asmall amount of voids can be produced by eluting a part of the fiberwhen refining is carried out.

The technique disclosed in the above cited United States patents isbetter than the other methods described above in view of the formationof voids in the fibers therein, but the object of the above cited UnitedStates patents is in the antistatic properties of the synthetic fiber,and therefore the techniques are inappropriate for simultaneouslyproducing the most desirable silky lustre and touch.

In addition, when melt-spinning polyamide with polyalkylene etherblended therein, various kinds of drawbacks, as described hereinafter,are brought about, and it is impossible to produce fibers of highquality at a high yield in accordance with the conventional techniques.

Namely, first of all, polyalkylene ether is not dissolved into thepolyamide, to say nothing of the low melting point and poor spinnabilitythereof, and therefore when polyamide and polyalkylene ether are merelymixed and the obtained mixture is melt-spun, the polymer melt isremarkably unstable as the polyalkylene ether of low melting point isseparated from molten polyamide. As a result yarn breakage occurs andspinning becomes im possible.

Secondly, in carrying out melt-spinning of the mixture prepared byblending polyalkylene ether and polyamide, when the mixture is spun withthe ordinary relatively low draft and the substantially undrawn yarnthus produced is contacted with an oiling roll where an oil finishcomprising an aqueous emulsion of spinning oil is applied, the undrawnyarn fibers are also adhered to each other (this phenomenon is generallycalled yarn-adhesion), and, as a result, the unwinding tension of thepackage when the undrawn yarn is drawn becomes remarkably greatproducing excessively overdrawn segments in such yarn. In addition, yarnuniformity is decreased and yarn breakage is common.

The object of the present invention is to provide a method for producingpolyamide fiber of excellent properties capable of smooth spinning bysolving the various problems heretofore associated with themelt-spinning of polyamide fibers having polyalkylene ether blendedtherein.

Another object of the present invention is to provide a method forproducing polyamide fiber having both silky lustre and silky touch bysubjecting the modified polyamide obtained in accordance with the abovementioned method to an appropriate after-treatment.

Another object of the present invention is to provide a method forproducing a polyamide fiber with a silky appearance and touch ratherthan the waxy touch and appearance peculiar to the usual polyamidefiber.

Further objects of this invention will become apparent from thefollowing description of the invention.

The present invention provides a method for producing polyamide fiberhaving improved silky lustre and silky touch, comprising the followingsteps;

(1) A polyalkylene ether, of excellent thermal stability i.e., notdecomposable at the melting point of the polyamide and substantiallyinsoluble in the polyamide, is blended with polyamide in an amountgoverned by the Formula 1 given below and modified polyamide pellets areprepared therefrom, in which fine particles of the above blendedmodifier are dispersed in such a manner that at least 50% by weight ofthe blended modifier comprises particles having an average diameterbelow 20p in their cross section;

(2) The modified polyamide pellets are then meltspun;

(3) After melt-spinning, the spun filament is continuously drawn untilthe birfringence, Art, of the spun filament satisfies Formula 2 below;

(4) The drawn polyamide yarn is then treated with a solvent for themodifier, to extract out a part or most of the modifier, thus producingvoids in the fiber.

Formulae (2) Arz l0 g49log (8a+8)32 (wherein a stands for millimols(mmols) of the recurring alkyleneoxide unit in the polyalkylene ethermodifier contained in 1 gram (g) of the polyamide; All is thebirefringence of a continuously melt spun, drawn yarn, taken up at 20 C.and 65% relative humidity after overnight exposure to the atmosphere, asmeasured by using the D-line emission of a sodium lamp.)

The fiber produced thereby, having certain specific physical propertiesas defined more specifically hereinafter, is also within the scope ofthe present invention.

When silky lustre and silky touch are produced, in accordance with thepresent invention, by blending polyalkylene ether along with polyamide,melt-spinning the obtained mixture into fiber, and washing the obtainedfiber, to extract the polyalkylene ether modifier, one of the mostimportant problems resides in the size and amount of the dispersedparticles of polyalkylene ether contained in the modified pellets beforespinning the fiber.

The polyalkylene ether is substantially insoluble in polyamide.

Further, the melting point of polyalkylene ether is low and it has poorspinnability. Therefore when polyalkylene ether is merely mixed withpolyamide, it oozes out onto the surface of the polyamide pellets duringthe meltspinning process. This polyalkylene ether on the surface of thepolyamide pellets acts as a lubricant causing the pellets to slip on thesurface of the screw in the melt spinning apparatus making the feedingof pellets very difiicult. In addition to this, when the two componentsof the pellets are melted, the polyalkylene ether is separated from thepolyamide. This causes yarn breakage at the spinneret, and substantiallyprecludes melt-spinning.

In addition when the dispersed particles of polyalkylene ether in themodified polyamide pellets are large in size, coarse voids are producedwhen the yarn obtained from the pellets is washed and extracted. Thismakes it difificult to produce the silky lustre which is desired.

In producing the present invention, it has been found that it isnecessary to melt-spin a modified polyamide containing finely dispersedmodified polyamide wherein at least half of the polyalkylene ethercontained in the modified polyamide is dispersed as minute particlesbelow 20a in diameter. This makes the supply of modified polyamidepellets flow smoothly into the screw extruder when modified polyamidepellets are melt-spun. It also prevents the separation of the twocomponents in the modified polyamide pellets and the desirable lustrewhen the yarn fibers are washed and extracted.

In regard to methods for finely dispersing polyalkylene ether inpolyamide, there are a number of such methods.

In one such method polyalkylene ether is added before or during thepolymerization of polyamide. In another method polyalkyene ether isblended with polyamide 4 pellets and thereafter the blended mixture ismelt-mixed by a mixing extruder which pelletizes the mixture.

However, it is difiicult, employing only the generally adoptedconditions, to blend polyalkylene ether with polyamide in such a mannerthat more than 50% by weight of the polyalkylene ether has a particlesize below 20 When polyalkylene ether is added during polymerization,the blending operation should be carried out under such conditions thatit can be uniformly dissolved into monomer or monomer solution. By sodoing, finely dispersed polyamide pellets, wherein the average particlesize of the modifier is around 5a, can be obtained.

On the other hand, it is preferable to carry out the pelletizingoperation by using a biaxial or triaxial screw extruder in order toeffect sufficient blending during the melt-kneading process.

The dispersed state of the polyalkylene ether modifier can be determinedby slicing the modified polyamide pellet with a microtome. The lateralcross section and longitudinal cross section thereof are then observedwith a microscope.

When the amount of the particles having a particle size below 20a is notmore than 50% by weight, the blend is re-melted and the kneadingoperation is repeated until pellets having modifier particles with morethan 50% by weight of the proper particle size are produced.

The modifier particles discussed herein include not only sphericalparticles, but also other particle shapes, such as rotary ellipse(elongated spherical) particles, linear, long fusiform (agglomerated)particles, etc.

As used herein particle size generally refers to the diameter of aspherical particle, or the diameter at the longitudinal midsection of arotary ellipse particle or for odd-shaped elongated particles, such asthe linear fusiform, the smallest cross-section diameter perpendicularto the axis of the particle. Collectively these may be referred to asthe diameter of the cross section of each particle.

In regard to the amount of the dispersed particles, the required amountthereof varies in accordance with the size of the particles, but as isdescribed hereinafter, the range of the amount of the dispersedparticles, wherein the desired properties are attained and the fiberprocessability is not degraded, is from 2 to 15% by weight. This rangewill be discussed in more detail hereinafter.

The second problem to be faced, in carrying out the melt-spinning andfiber shaping process with polyamide containing finely dispersedpolyalkylene ether particles, is the mutual yarn-adhesion of fibers asthey are taken up in the aqueous emulsion of spinning oil.

This yarn-adhesion remarkably increases the unwinding tension of thepackage, when the undrawn yarn is drawn, causing yarn breakage orunevenness of yarn properties. As a result, the production of drawn yarnis made practically impossible.

In addition, the yarn-adhesion is retained in the final product and acoarse hand, like plait yarn, is retained in the final product.

In accordance with the present invention, the above mentioned problemcan be solved by continuously drawing the melt-spun undrawn yarn, priorto taking it up, until the birefringence of the yarn satisfies Formula2.

By so doing, the yarn-adhesion of the yarn or filament can be preventedas the modified polyamide containing polyalkylene ether is melt-spun,and has absorbed water content from the spinning oil or from the air.

The swelling elongation due to absorption of water content can becontrolled by increasing the degree of orientation above somepredetermined value.

In the drawings:

FIG. 1 is a schematic illustration of a melt-spinning and drawingprocess as used in the present invention;

FIG. 2 is a graph of modifier content versus birefringence of a drawnyarn with no yarn-adhesion in the present invention;

FIG. 3 is a diagrammatic illustration of the process used for measuringcertain optical properties of the fiber of the present invention, and

FIG. 4 is a graph of certain optical properties used to determinequantitatively one important optical property of the fibers of thepresent invention.

Referring now to FIG. 1 there is shown a diagram of an embodiment of thedevice for carrying out the method of this invention for producingpolyamide fiber. More specifically there is shown polyamide fiber 1extruded by spinning nozzle 2 from a melt of modified polyamide preparedby blending polyalkylene ether in polyamide. And then it is contactedwith oil roller 3 where an oil finish is applied, and is then passedfrom draw feed rollers 4, to drawing rollers 5 revolving at higherperipheral velocity than that of draw feed rollers 4.

The degree of orientation required for controlling the yarn-adhesion ofyarn or filament can be determined from the amount of the polyalkyleneether blended with polyamide, in accordance with Formula 2 given above.The reason for this is that the yarn-adhesive is mainly caused bypolyalkylene ether. A plot of this relationship is given in FIG. 2,wherein the area bounded by the parameters given in Formulas 1 and 2 isshown by slant lines.

When the amount of polyalkylene ether contained in l g. of polyamide isless than 0.2 mmol, the optical property of the fiber, with a part orall of the polyalkylene ether blended therein extracted therefrom, isnot silky. When the amount of polyalkylene ether contained in 1 g. ofpolyamide is more than 3.5 mmol, yarn breakage or yarn-adhesion becomesexcessive and spinning becomes very difficult even if the polyalkyleneether is finely dispersed in the polyamide. At the same time when theamount of polyalkylene ether is more than 3.5 mmol, yarn produced has nosilky lustre but becomes chalky when the obtained yarn is washed andextracted.

As is apparent from the diagram of FIG. 2, the minimum birefringence is40-45 1()- at maximum polyalkylene ether concentration. Thisbirefringence is required for preventing yarn-adhesion when thepolyamide which contains the possible maximum amount, i.e., 3.5 mmol/ g.of polyalkylene ether, is melt-spun. The minimum birefringence is closeto that of the drawn yarn, as the amount of polyalkylene ether islowered and the required birefringence for controlling yarn-adhesion istherefore also lowered.

On the other hand, the birefringence required for controllingyarn-adhesion, has a tendency to be more or less changed in accordancewith the structure of polyalkylene ether and the kind of the matrixpolyamide, but the difference is not so great as the effect of theamount thereof to be added.

In particular, when the molecular weight of polyalkylene ether isincreased, the birefringence can be determined substantially by theconcentration of alkylene oxide radical in the polyamide.

In the present invention, a polyalkylene ether having a molecular weightfrom 600 to 60,000 may be used but a molecular weight of from 1000 to20,000 is preferred.

The structure of polyalkylene ethers having a molecular weight withinthe above mentioned range greatly affects the properties of the yarnproduct and the melt-spinnability of the modified polyamide.

As the alkylene oxides upon which the modifiers used in the presentinvention, eg the polyalkylene ethers or addition products thereof, arebased, ethylene oxide or propylene oxide are preferred.

In accordance with the present invention, the polymer prepared by addingan alkylene oxide to organic compounds containing active hydrogen, suchas a homo-or-copolymer of propylene oxide, organic amines, alcohols,acids, and compounds Whose terminal hydroxyl radicals are confined, ormixtures of said compounds, can be used as the polyamide modifier. Butin order to obtain excellent spinnability, polyalkylene ether havinghigh affinity for polyamides, such as alkylene oxide adducts ofpolyamide oligomers or polyamide monomers containing amido radical inthe molecule thereof are preferred. The preferred compounds includeethylene or propylene oxide addition products of tetragonal throughtridecagonal lactams, such as Z-piperidone, e-caprolactam,enantholactam, laurin lactam and other similar alkylene oxide additionproducts.

As an example of a method for making the polyalkylene oxide additionproducts, 1100 parts of ethylene oxide was subjected to additionpolymerization along with 127 parts of enantholactam in the presence of0.1 part of potassium hydroxide catalyst at the reaction temperature ofC. under the reaction pressure of 43 kg./cm. for the reaction time ofabout 5 hours.

Upon analysis, it was determined that 23 mol of ethylene oxide per gramenantholactam had been added, on the average, and the product thusobtained was a light yellow paste.

Moreover, in order to prevent coloring of the polyamide caused by heatand the modifier blended therein, it is preferable to blend therewith aphosphoric ester and/ or the metal salt thereof. As the metal radical ofthe metal salt, mention can be made of such, for example, as the alkalimetals as Na and K, the alkaline earth metals as Mg, Ca, and Ba, thetransition metals as Cr, Co, Cu, Zn, Sn, Mn, and Ni, and A1, of whichthe most convenient are the transition metals, particularly, Mn Cu, Co,and Ni.

As examples of such phosphoric esters, monoesters, diesters, triestersor mixtures thereof can be given.

At any rate, those having high afiinity for alkylene oxide and of astructure, capable of being easily extracted with solvent, arepreferred.

In the present invention, it is necessary that the meltspun and drawnmodified polyamide containing polyalkylene ether be washed with asolvent which is inert against polyamide and active against the modifierblended therein so that a part or most of the modifier is extracted(from the fiber. It is also necessary that the appropriate amount ofvoids be formed in the fiber.

As the proportion of the modifier extracted is increased, the silkyappearance and lustre effect of this invention can be attained withlower concentrations of modifier in the melt-spun fiber.

For the extraction, it is preferable to use an organic solvent such asalcohol or benzene.

In order to produce silky lustre and high non-transparency as describedhereinafter, it is preferable that the extraction should be carried outin such a manner that the amount of voids in the fiber is within therange from 0.5-l3 vol percent.

When the amount of the produced voids is less than 0.5 vol percent, thesilky touch and lustre is not attained.

On the other hand, in order to exceed 13 vol percent voids it isnecessary to blend approximately 20 wt. percent modifier, and thereforeseparation of polyalkylene ether and polyamide occurs, as mentionedbefore and melt spinning becomes impossible. Further, the fiber productis chalky and scatters light too much.

Extraction can be carried out on yarn, but it can also be carried out onthe textile product made from the yarn. Generally it is preferable tocarry out extraction on the textile product from an industrial point ofview. As used herein textile product is a product knitted, woven, orotherwise made up of fibers such as those of the present invention.

To further improve the lustre of the product of this invention finewhite particles may be blended in the fiber forming material. This mayalso improve the processability of the fiber.

However, care should be taken with respect to such particles andparticularly to the particle size and the blending proportion thereof sothat the excellent fiber processability and silky lustre of the presentinvention is not lost. Namely, the diameters of circles circumscribedaround these particles (e.g. the maximum diameters of the particles)should not be above or more than /a of the diameter of the melt spunfiber.

When such particles above 10a are blended in the polyamide, theseparticles clog the filter during meltspinning. Melt spinning thusbecomes very difficult and the properties of the yarn product areremarkably degraded. The preferable size of these fine white particlesis such that the diameters of circles circumscribed around the particlesis from 0.1 to 4a. In order to obtain particles of preferred oracceptable particle size, a conventional method, such as hydarulicelutriation, is appropriate. A dispersing agent may be used whenblending of the fine white particles is carried out during thepolymerization of polyamide.

As the fine white particles which may be coemployed along withpolyalkylene ether modifier in the present invention, the commerciallydistributed inorganic or organic white pigments can be used. But finewhite particles the refractive index of which differs too greatly fromthe refractive index of polyamide (whose refractive index is about 1.56)scatter too much light at the interface between the particle and thepolyamide matrix, making the product frosted. Therefore the silky mildlustre which is the characteristic of this invention is lost. Thus theamount of fine white particles to be blended with the polyamide is morelimited if the difference of the refractive index between the particleand the polyamide is too great. As a result of detailed study into thismatter by the inventors of the present invention, it has been 'foundthat the difference of refractive index between the polyamide matrix andthe fine white particles to be blended and the amount thereof shouldsatisfy the following Formula 3.

(wherein C is the amount of fine white particles to be blended (weightpercent); d is the absolute value of the difference of refractive indexbetween the fine white particles and the polyamide).

When fine white particles are blended by such an amount as to satisfyFormula 3, it is possible to improve the processability of the yarn bylowering its frictional coeflicient without losing the silky lustreproduced in accordance with the present invention.

When the amount of the fine white particles blended into the polyamideis more than the amount defined by Formula 3, the yarn product becomeschalky and the lustre, otherwise produced in accordance with the presentinvention, is not obtained.

As fine white particles, the following are preferred: (The figures inparentheses show the refractive index of each type of particle.)

Halloysite (1.56)

Kalolinite (1.56)

Metakaolin (1.60) and such like kalin group Talc (1.59)

Pyrophillite (1.59)

Calcium carbonate (1.67) Magnesium carbonate (1.51, 1.70) Silica (1.4,1.5)

Zinc oxide (2.02)

Titanium oxide (2.50 or 2.75) Zinc sulfide (2.37)

The term polyamide as used herein, refers to meltspinnable polymers ofpolymerizable 'monoaminomonocarboxylic acids, salts of diamine anddicarboxylic acid, or melt-spinnable fiber forming polyamides obtainedfrom the amido forming derivatives thereof.

Copolymer of two or more of the foregoing can also be used.

The preferred polyamide used in this invention are polye capramide,polyhexamethylenedipamide, polyhexamethylenesebacamide. Other aliphaticpolyamides, polyamides having aromatic rings, aliphatic rings orheterocycles in the main chain can also be used.

Heat stabilizers, light stabilizers, dyes and homologues of theforegoing polyamide materials may also be blended in the polyamides usedin this invention.

The improved polyamide fibers obtained in accordance with the presentinvention have from 0.5 to 13% by volume of finely dispersed voids inthe fibers and have a surface lustre such that the ratio of the strengthof scattered light (I/I as defined hereinafter) satisfies the Formula 4below. At the same time the lustre factor (a as defined hereinafter)satisfies the Formula 5 below.

Formula 4 Formula 5 Further, the polyamide fiber of the presentinvention has high non-transparency.

The polyamide fiber having such lustre properties as mentioned above,has a silky appearance, and is free of the waxy appearance peculiar tothe usual synthetic fiber.

In this invention the reflectivity of the fiber is measured by the ratioof the strength of scattered light (I/I which is determined in thefollowing manner, as illustrated in FIG. 3.

A test sample (S) is prepared by winding a test fiber on anon-reflective black panel in such a manner that the successive ends oftest fiber lie in parallel and in contact with one another and there isno space between the respective adjacent test fiber ends.

This test sample (S) is set on a sample stage and white parallel lightis projected onto it perpendicularly to the fiber axes of the testsample at the incident angle, O=45. The strength of reflected light (I)at the light receiving angle, 0 =45, is measured with a photoelectricphotometer (Jyonan Manufacturing Co., Ltd., Model JSG-21').

The strength of reflected light (I of a standard white board ofmagnesium oxide (HS-Z 8722-1959) is measured under the same conditions.

When the ratio of the strengths of scattered light, N1 is high, thewhole fiber is made to shine brightly by incident light. When this valueis low, the brightness of the whole fiber is lower.

The lustre factor (a) of the present invention is a measure of lustrequality, and it is obtained in the following manner. The sample panel(S) is prepared by winding fibers in the same manner as described above.The light is projected onto the sample panel at the incident angle,O=45, while the sample (S) is rotated horizontally around the verticalaxes of the sample plate. The reflected light (I) strength in thedirection of the light receiving angle 45 (the angle of reflection on amirror surface) is continuously measured during rotation.

The strength of reflected light (I) is plotted against the angle ofrotation of sample (S) rotating in the plane of sample (S), and a curveas is shown in FIG. 4 is obtained.

The lustre factor (a) is defined as the range (AB) of the angle ofrotation in which the strength of reflected light exceeds the meanstrength, which is the average value of the maximum strength ofreflected light (I max.) and the minimum strength of reflected light (1min.) of said curve in any half revolution of sample (S).

The lustre factor (a) shows the angular range in which the fiber looksbrighter than the mean brightness of the fiber at the angle of mirrorreflection thereof.

When the lustre factor is greater, the fiber or bundles thereof lookbrighter when light is projected onto the fibers assembled in a textileproduct (wherein the axes of the fibers comprising the product are invarious directions).'

On the other hand, when the lustre factor is smaller, the only fiberswhich appear bright are those fibers aligned in a specific direction(wherein the axis of the fiber is parallel with the plane including theprojected light direction). In such a case, the product appears to havelow lustre.

Therefore, unless the ratio of the strength of scattered light (l/I andlustre factor (a) satisfy the Formulae 4 and 5, a polyamide fiber havinga mild and cool touch and a silky lustre, is not obtained.

The optical properties of polyamide fibers produced in accordance withthe present invention are compared by taking as examples the fibers asusually used for clothes (the unit filament size being 3 denier). Thiscomparison is graphically illustrated in FIG. 4.

As is generally known, silk has high covering power and a mild, socalled, silky lustre. FIG. 4 shows the reflection pattern of silk (Curve4) measured by the same instrument and in the same way used forpolyamide fibers, as described herein.

The ratio of the strength of scattered light (I/I is high in the case ofnatural silk, and the lustre factor (a) is also high.

Conventional unmodified polyamide fiber (Curve 2), containing notitanium oxide, also has a high ratio of strength of scattered light.However, it has a very low lustre factor; accordingly the transparencyof the conventional polyamide fiber is high and therefore when light isprojected from a specific direction, it glistens and presents a waxyappearance and strong touch.

With a polyamide fiber (Curve 3) containing titanium oxide to increasethe non-transparency of the fiber, the diffused reflection of light onthe surface of fibers is increased and the lustre factor (a) isincreased, but the ratio of the strength of scattered light (I/I withinthe plane inclusive of the projected light is poor. Therefore, the fiberis dull, and chalky and when such a fiber material as this is dyed, adull pastel like lustre is obtained.

However, the improved polyamide fiber (Curve 1) of the present inventionhas high non-transparency, lustre factor (7) is high, and the ratio ofstrengths of reflected light (l/l is remarkably high. Generally, itpresents a lustre similar to that of a natural silk. Therefore, when itis dyed, very brilliant colors can be obtained.

In regard to the blending of white fine particles in the fibers of thepresent invention, when such blending is carried out under appropriatecondition in accordance with Formula 3 above, it is possible to producethe polyamide fibers which satisfy both Formulae 4 and 5 above.

It should be noted that the improved polyamide fiber of the presentinvention must satisfy both Formulae 4 and 5 simultaneously.

When the ratio of the strength of scattered light (I/I is less than 1.5,the amount of the reflected light is very little as light is projectedonto the fiber bundle, and the fiber bundle has insutficient brightness.

On the other hand, when [/1 is larger than 15, the strength of lightreflection in the position of mirror plane reflection is too high andthe fiber group glistens like a mirror. This is undesirable.

When the lustre factor (a) is less than 20, the fiber bundle sparklesonly in a specific direction (generally in the direction parallel withthe fiber axis) as light is projected onto the fiber, and it is notpreferable.

On the other hand, when lustre factor (a) is larger than 90, the wholefiber presents a dull and chalky appearance and this therefore is notdesirable either.

When the polyamide fibers obtained as described in the foregoingparagraphs are used to prepare textile products, these products have acompletely different lustre than that of textile products woven fromconventional synthetic fibers. When the textile product woven from theFrom the weight of the modifier extracted by a solvent therefor and thedensity thereof, the volume previously occupied by the extractedmodifier is determined and from this the volume percent voids iscalculated.

(2) Size of void:

Void size is determined from an electron microscopic photograph of alateral cross section of the filament.

(3) Transparency of fiber:

Fibers are associated into tow of 28,000 denier, and this tow is madeinto a blind the width of which is 2.5 cm.

This blind is set on a photoelectric photometer (produced by NipponPrecision Optical Co., Ltd., Model SEP-H), and the permeability ortransparency (percent) with respect to white light of a tungsten lamp ismeasured.

(4) Dispersed state of modifier contained in polyamide pellets:

The central portion of a pellet is cut into pieces (the thickness of thelateral cross sectional surface and longitudinal cross sectional surfaceof each piece being respectively 5 to 10p.) and the obtained pieces areobserved with a microscope to determine the diameters of the dispersedparticles and the number of particles in the pellet cross section.

( 5 Birefringence Polyarnide fiber having been spun, drawn and taken up,is left out in an atmosphere of 20 C., 65% relative hu midity, for 24hours, and then the birefringence of the fiber is measured by using theD-line emission of a sodium lamp with a polarizing microscope.

(6) Yarn-adhesion The presence or absence of yarn-adhesion is judged bythe degree of flattening observable in the yarn bundle due to the mutualyarn adhesion or in the case of multifilament yarn by the unwindingtension of the yarn package.

Hn the case of the yarn bundle having adhesion, a Becke line, which isgenerally present on both contacting surfaces of yarn when the lateralcross section of fiber is observed with a microscope, cannot beobserved; but when no adhesion is present, a Becke line can be observed.

(7) Sulfuric acid relative viscosity (777) The relative viscosity of thesolution prepared by dissolving 1.0 g. of dry polymer into cc. of 98%sulfuric acid. Viscosity is then measured using an Ostwalds viscometer.

(8) Dynamic frictional coefiicient d) The sample filament yarn is workedon a frictionless roller (whose diameter is 10 mm. and fixed to theframe), and the filament yarn is twisted to give three turns thereto.Then the tension before the roller is determined to be 5 g., and whilerunning the yarn at the speed of 300 m./ min., the tension (T) after theroller is measured, and the value obtained in accordance with thefollowing formula is the measure of the dynamic frictional coefiicient.10

3,734,986 11 12 EXAMPLE 1 spun, irregular extrusion was brought aboutright after 5 parts of ethylene oxide addition product enantholactheSpinning Was n tiated Frequent fibe hfeakages tam (Modifier No. 1,addition product of 100 mol of curred as a result, taklhg P of the Y wasSubstah' ethylene oxide) was mixed along with 100 parts of polytiallyimpossible.

TABLE 1 Drawn w g. SamplcNo; Pellets Spinning method Extruded StateDrawn state (X104) Ctmtroll A Direct spinning drawing method Poor;frequentbreakage of yarn..'... Take-up impossible Example 1 B doExcellent Excellent 45 Control2 B Conventional spinning drawing ...d0Frequent yarn breakage 48 method.

e-capramide (nylon 6) (1 r=2.46). This mixture was When Pellets B ofexcellent dispersion was used as in kneaded and fed to an extruder.After having been meltthe case of Control 2, extrusion was carried outnormally mixed at 260 C., it was pelletized. and there was no differencefrom the conventional un- The pellets thus obtained (hereinafterreferred to as modified nylon 6. But when the conventional drawingPellets A) were dried at 110 (under a reduced pressure), method wasused, the unwinding tension of the package and the water content wasadjusted to be below 0.05%. m u drawn yarn Was remarkably great, and atthe The concentration of oxyethylene radical contained in same timeunevenness of drawn yarn was great. Therefore the polymer was 1.1mmoL/g. corresponding to 4.8 yarn breakage was frequent when the yarnwas drawn. i ht percent However, in Example 1 obtained in accordancewith Th l t l cross section of P ll t A was ob d the present invention,uniform extrusion was very exwith a microscope and the dispersed stateof said modieehehtly Carried Further, there Was 110 y breakage fier wasstudied. As a result of this observation, it was at the drawing Zone anduniform drawn y Could be determined that the modifier was in a lineardispersion Obtainedwherein the mean particle size was 15 and the lengthThe drawn y p of excellent Spinning and th f was 500400,, and more than50% by weight f drawn state produced in accordance with the method ofthe coarse particles were observed to have a particle size the Presentinvention and the unmodified nylon 6 above 20 trol 3) prepared inaccordance with the same method Next, these Pellets A were revelletized,ft having as in Example 1 without blending a modifier therein were beenkneaded with a biaxial screw extruder of excellent respeetlvely Wound inthe form of ks. These hanks kneading property, and the newly obtainedpellets (lierein- Were pp into hbt Water sutheientty shaken p afterreferred to as pellets B) were dried under reduced 30 minutes and thenpp into hOt W t r f r pressure in the same manner as in the case ofPellets A. about 30 mthhtesy Were then dehydrated and d- The dispersedstate of the modifier in these pellets was AS a result of themeasurement of the Change Of Weight also studied and it was found thatmore than 70% by before and after the Washing of the modified nylon 6weight of said pellets were dispersed in alinear dispersion 40 of thePresent invention, it Was nd ut that about wherein the particle size wasabout 8;/., the length thereof 80% of the first blended modifier yWeight of was from 600 to 700,14, and coarse particles (having a nylonWas extracted y the hot Water Washing and particle size above 15,14)could hardly be observed. Voids wel'e Produced in the fibers- Pellets Aand Pellets B were supplied respectively into The Void etlpaeity Wasabout 33% y Volumeconventional melt-spinning hi d me1t spun at 45 Thelateral cross section of fibers thus obtained was 250 C. Th re ft thespun yams were taken up at 800 observed with an electron microscope andas a result of m./min., and thereafter the yarns were draw o a themicroscopic observation, it was found that the averond roller running ata peripheral speed of 2,800 m./min. age diameter of these Voids Was andthe maximum Then they e tak up t producs drawn yarns f 70 diameterthereof was 1.5,u. Further, it was found that there d i 24 filaments wasno void with a diameter of more than (about 2,)

The drawn yarn produced by using Pellets A was made bf the diameter ofthe fiber- Control 1, the drawn yarn produced by using Pellets B Theratio of the Strength of Scattered o) and wa d E l 1 lustre factor (a)of the modified and unmodified nylon 6 A separate sample of yarn d d frPellets B fiber having been extracted as mentioned above, were was takenup as undrawn yarn at 800 m./min. in the same measured, and the resultsare given in Table manner as in the conventional spinning drawingprocess. The modified hylbh 6 fiber of the Present invention had Afterhavi b l ft o t overnight hi yam was drawn a ratio of the strength ofscattered light and lustre factor four times by using a conventionaldraw-twister to prowhich satisfies both Formula 4 and Formula More du edrawn yarn, over, the modified nylon 6 fiber of this invention pre- Thiyarn a th m d C t l 2 sented a bright lustre and, in addition, veryexcellent non- Table 1 shows the melt-spinning state of all of thesetransparency and y and Warm touch Were obtahledyarns, the drawing statethereof, and the birefringence on the other hand, the unmodified nylon 6had low of the drawn yarns. ratio of strength of diffused light, lowlustre factor, and

When the Pellets A, wherein polyalkylene ether is high transparency.Further it had a waxy touch and coarsely dispersed in the modified nylon6, was meltappearance.

13 EXAMPLES 2-4 The polyalkylene ether obtained by adding 45 mol ofethylene oxide to a mole of sterylalcohol in accordance with aconventional method was phosphoric-esterified by using phosphoruspentoxide in accordance with a conventional method. This product wasthen neutralized with calcium hydroxide. Thus, Modifier No. 2 wasprepared.

Six parts of Modifier No. 2, 100 parts of e-caprolactam,

14 The modified polyamides of Examples 24, having no yarn-adhesion andexcellent spinnability were washed under the same conditions as inExample 1 to extract the modifier. Thereafter the ratio of strength ofdiffused light and 0.13 part of acetic acid, as a viscosity stabilizer,were mixed, and water was added to the mixture to make 75% aqueoussolution. With the modifier uniformly dissolved the solution waspolymerized in accordance with a conventional method.

The modified poly-e-capramide (nylon 6) product was washed with largeamounts of pure water (at 9095 C.) to remove unreacted lactam andoligomer, and then dried under a reduced pressure.

The concentration of modifier was 5.2% by weight, (the concentration ofoxyethylene radical was 1.2 mmol/ g.) in the modified nylon 6, and therelative viscosity of the polymer was 2.45.

The modifier was very finely dispersed in the polymer and more than 80%by weight of fine spherical particles, with a particle size of 2p, waspresent.

This modified Nylon 6 was supplied to a conventional spinning machineand the melt spun yarn was taken up initially at a speed of 900 m./min.Then the speed of the drawing roller was changed and the yarn prior tobeing taken up was drawn under such a condition that variousbirefringence as shown in Table 3 were obtained.

The output of extruded polymer was changed in accordance with thedrawing rate so as to produce 70 denier-24 filament drawn yarn. Theyarn-adhesion of the drawn yarn is shown in Table 3.

The state of extrusion was excellent in all cases, but the yarn whosebirefrigence, An, was low, which was drawn under such conditions thatFormula 2 was not satisfied, had great unevenness, the yarns thereofwere adhered to one another, and in the extremity, yarn breakage wasbrought about when the yarn package was unwound.

When An goes beyond 30 10 yarn-adhesion was reduced to such a degreethat it did not matter any more and unevenness of yarn was remarkablylow.

When the drawing speed goes beyond 4000 m./min., yarn-adhesion is ofcourse eliminated, but the elongation of the drawn yarn becomesextremely low, and therefore yarn breakage is frequently brought about,making fiber forming substantially impossible.

The birefringence of the limiting drawing rate was 5 2 x EXAMPLES s-se-Caprolactam-ethylene oxide addition product having a molecular weightof 4733 (referred to as Modifier No. 3) was prepared by adding 105 molof ethylene oxide per 1 mol of e-caprolactam. This was blended alongwith e-caprolactam in amounts ranging from 0.1 to 4.1 mmols ofoxyethylene unit per gram of e-caprolactam as shown in Table 5.

Each of these mixtures were mixed along with water to prepare aqueoussolutions.

In each case aqueous solution, which was transparent and in which themodifier was uniformly dissolved was put into a polymerization vesseland heated under atmospheric pressure, while the reaction mixture wasstirred with an efiicient stirrer provided with spiral blades. Thestirring operation was initiated at the point in time when the modifierbegan to separate and the stirring operation was continued until thepolymerization was terminated.

These polymer products were melt-spun and cooled and thereafter theunreacted monomer was washed out with water and the modifiedpoly-e-capramide thus produced contained Modifier No. 3, in amountsindicated in Table 5, which was separated from the polyamide phase andwhich was in the form of fine spherical particles, with an averageparticle size of 4a.

In the product prepared by blending 4.1 mmol/g. of modifier which isoutside the range of this invention (from 0.2 mmol/g. to 3.5 mmol/ g.)the modifier and the polyamide showed a great tendency to separate,preventing the polymerization of nylon 6 and the spinning of yarn fromthis particular pellet material.

Examples of each of the remaining types of modified nylon 6 pellets weresupplied to the screw type spinning machine, and were passed through thespinning nozzle pack, provided with a filter charged with 60 mesh and200 mesh white Alundum, to melt-spin the modified nylon. Then theextruded fiber was taken up at a speed of 900 m./min. and thereafter itwas continuously drawn.

The drawing operation was carried out on modified nylon 6 productscontaining Modifier No. 3 at several drawing speeds and substantially noyarn-adhesion was observed, no yarn breakage was brought about, andexcellent drawn yarn was obtained.

The birefringence of the yarns thus obtained are given in Table 5.

As the amount of modifier is increased, yarn-adhesion occurs and theminimum birefringence must be increased.

Those having an insufiicient degree of orientation among the abovementioned drawn yarns, were drawn again by using a conventionaldraw-twister, and drawn yarn (50 denier/ 17 filament), the elongation ofwhich was from to was obtained.

In the same manner, nylon 6 fiber (whose elongation was from 35 to 40%)was prepared by blending 0.3 and 2.0% of titanium oxide along withunmodified nylon 6 and unmodified nylon 6 containing no modifier at allwas obtained.

The above prepared modified polyamide fibers were wound in hank form anddipped into 40 C. hot water. Then they were shaken and stirred for about30 minutes.

Thereafter, they were dipped into 80 C. hot water, for about 30 minutes,to deoil the same, and then water was removed from the hanks and theywere dried.

In both of the hank, from 50 to 80% of the modifier was extracted with40 C. hot water.

As a result of microscopic observation of the lateral cross sectionalsurface of the fibers, voids, the mean diameter of which was 0.2 wereobserved in the polyamides prepared by blending modifier therein and apart of which was subsequently extracted.

The ratio of the strength of scattered light (I/I lustre factor (a),transparency, and the amount of voids in the polyamide fibers, weremeasured, and the results of these measurements are given in Table 5.

In the modified polyamide fiber of the present invention the amount ofvoids increases as the amount of modifier added increases. Along withthe increase in the amount of voids, the transparency of the fibers isreduced, and the ratio of the strength of diffused light (U1 and lustrefactor (a) are increased.

In the case of the modified polyamide fiber obtained in accordance withthe method of the present invention, when the modified polyamide fiberof Control 9, which contains 0.2 vol percent of voids, is taken as anexample, the improvement of lustre is not sufficient, and the ratio ofthe strength of diffused light (U1 and lustre factor (a) are also closeto those of the unmodified polyamide fiber of Control 6.

However, the fibers of Examples 58 which have a sufficiently high ratioof strength of diffused light (U1 and lustre factor (a), to satisfy therequirements of the present invention, are non-transparent and have abright lustre.

A Tricot weave of these fibers had a mild and silky lustre and, whencompared with the product prepared by blending 0.3% by weight oftitanium oxide, it had higher non-transparency, and presented a warmerand dryer touch.

On the other hand, the unmodified polyamide fiber of Control 6 had alower ratio of strength of scattered light (U1 and lustre factor (a) andglistened only when observed from a specific direction. Further, it wasremarkably transparent and had a waxy touch. Generally its appearancewas harsher.

The polyamide fibers of Controls 7 and 8 prepared by blending titaniumoxide had much lower ratios of strength of diffused light (U1 and thefibers generally presented a dull lustre. The appearances thereof waspastel colored.

At any rate, all of these controls were inferior to the modifiedpolyamide of the present invention insofar as silky lustre is concerned.

For comparison, the lustre of natural silk having been refined withalkali in accordance with the conventional method was also measured andthe result is given in Table 5.

The lustre of the polyamide fiber of the present invention is very closeto that of natural silk as is apparent from Table 5.

TABLE 5 Concentra- Minimum Contents tion of birefringence of modifieroxyethylene Contents incapable of in nylon 6 units causing yarnpellet(wt. (mmol/g. titanium adhesion to percent) nylon) dioxide the yarnControl:

1. 8 0. 4 0 20Xl0- 5.3 1. 2 0 31x10- 8. 8 2.0 0 37X10- 13. 4 3. 0 044X10- 18. 2 4. 1 0 11 (silk) 1 No. yarn-adhesion. 1 Not polymerized.

Void in the fiber Ratio to after strength of extraction scattered LustreTrans- (vol./ light factor parency percent) (H1 (01) (percent) EXAMPLES9-11 A slurry composed of parts of laurolactam and 30 parts of water,was charged into an autoclave, and the mixture was heated in accordancewith the conventional method, and polymerization was carried out under ahigh pressure.

The internal temperature of the autoclave was 300 C. and the pressurewas controlled to be 18 kg./cm. Under these reaction conditions, 6 partsby weight (concentration of oxyethylene radical is 1.3 mmol/g. oflactam) of the molten ethylene oxide addition product of e-caprolactammol ethylene oxide/mol of e-caprolactam was added thereto) was blendedwith the laurolactam, and the polymerization was terminated.

The modified nylon 12 pellets obtained by melt-spinning and cooling thisreaction product had a sulfuric acid relative viscosity of 2.0.

These pellets were sliced and microscopic observation was carried out,as a result of which it was found that the modifier was finely dispersedin the form of fine spherical particles whose particle size was from 4to 6a.

In the same manner as before, unmodified nylon 12 (whose relativeviscosity was 2.2) was prepared without blending modifier therein.

The modified nylon 12 was supplied into an extruder type spinningmachine, and it was melt-spun at 280 C. and taken up at a speed of 800m./min. Thereafter the yarn was drawn with a drawing roller running at aperipheral speed of 2400 m./min. by using the same device as in Examples2-4, and then the drawn yarn 30 denier/ 6 filament was taken up.

The elongation of the drawn yarn was 40%, and the birefringence thereofwas 41x10? Yarn-adhesion was not observed at all and no yarn breakagewas observed. The spinning operation was carried out very excellently.

This yarn was divided into four groups, and then the respective groupswere wound on hanks, and the respective hanks were subjected toafter-treatment.

One of the hanks was not subjected to the after-treatment and this wastaken as Control 2.

The second hank was subjected to extraction by using boiling Water for30 minutes and the hank thus treated was taken as Example 9.

The third hank was treated with 40 C. hot water for 30 minutes, and theyarn thus treated was taken as Example 10.

The last hank was boiled in a mixture of methyl alcohol and benzene,mixed at a ratio of 1:1, for 30 minutes and the yarn thus treated wastaken as Example 11.

The lateral cross sections and side views of the above mentioned yarnswere observed with a microscope, and as a result it was found thatuntreated yarn has no voids; this yarn Was also transparent. But theyarn which had been treated with boiling water, and that which had beentreated with 40 C. hot water, had voids which were long and had anaverage diameter of 0.5

The amount of voids in the case of the latter was remarkably greaterthan that of the former.

The ratio of the strength of scattered light, lustre factor, andtransparency of the respective yarns described above were measured usingthe same method used in Example 1. The results thus obtained are givenin Table 6.

As is apparent from Table 6, the optical property of modified nylon 12from which the modifier had not extracted (Control 2) was not muchdifferent from unmodified nylon 12 having no modifier.

On the other hand, modified nylon 12 treated with boiling water, warmwater or organic solvent (Examples 911) presented a high ratio ofstrength of scattered light (I/I lustre factor, and excellentnon-transparency and presented a silky lustre and a dry and desirabletouch.

However, different effects were observed in the various examplesdepending on the solvent used to extract the modifier. Namely, whenboiling water was used for extraction, the extracting effect was worse.Warm water produced a good effect, and organic solvent produced the bestresult.

When a large effect is to be obtained by blending a small amount ofmodifier, it is preferable to use organic solvent as in Example 11.

were transparent and the modifier in each case was uniformly dissolvedinto the nylon 6.

In the pellets prepared by adding the modifiers having the larger moleratio of ethylene oxide in each of the pairs of addition products, themodifier was separated from the nyon 6 and the modifier was finelydispersed in the form of spherical particles the average diameter ofwhich was from 3 to 5 The modified nylon 6 pellets containing the abovementioned modifiers were then melt spun as in Examples 2-4.

The melt temperature was 265 C., the take-up speed was 600 m./min., andthe drawing speed was 1900 m./ min. Drawn yarn (70 denier/24 filament)was obtained.

The birefringence of the above modified nylon 6 products were about 4510 and no yarn-adhesion was observed.

However, the yarn breakage of the molten polymer at the outlet of thespinning nozzle was different depending on the structure of themodifier. Remarkable yarn breakage was observed in the case of nylon '6yarn prepared by blending the nonylphenol ethylene oxide additionproduct and, in addition, the modifier was separated from the a nylon 6.More specifically, it oozed out onto the surface of the pellets. Thiscaused the supply of pellets to be very unsteady and irregular extrusionresulted.

However, in the case of the nylon 6 prepared by blending the ethyleneoxide=e-caprolactam addition product, which has better aflinity fornylon 6, such problems in meltspinning did not occur and spinning wascarried out excellently.

The above mentioned modified and unmodified nylon 6 yarn and unmodifiednylon 6 yarn prepared by blending no modifier were extracted in the samemanner and under the same conditions as in Example 1 to extract themodifiers. Thereafter the yarn products were taken up in the form ofblinds, and the ratios of strength of diffused light (I/I lustrefactors, and transparencies thereof were measured.

TABLE 6 Void after Ratio of the Amount of extraction strength of LustreTransmodifier Extracting (vo1./ scattered factor parency (percent) agentpercent) light (I/I) (a) (percent) Control 12.. 5.7 None None 4.1 7.7 59Example:

9 5.7 Water (100 C.)-- 1.5 4.9 42 35 10 5.7 Water O.)- 3.5 5.7 48 24 115.7 Methyl alcohol- 4.3 6.2 49 20 benzene mixture (65 (3.). Control 13-.0 None 0 6.2 6.1 58

As 15 shown in Table 7, no voids were produced 1n EXAMPLES 12-14 Each oftwo kinds of e-caprolactam ethylene oxide addition products (the molarratios of ethylene oxide to caprolactam being 10 mol/mol and 40mol/mol), each of two kinds of lauryl alcohol ethylene oxide additionproducts (molar ratios of ethylene oxide to lauryl alcohol, 5 mol/moland 40 mol/mol) and each of two kinds of nonylphenolethylene oxideaddition products (molar ratios of ethylene oxide to nonylphenol 5mol/mol and 40 mol/ mol), i.e., 6 kinds in all of modifiers, wereblended in a proportion of 1.3 m. mols of oxyethylene unit per gram oflactam, with e-caprolactam. These mixture were polymerized under thesame conditions as in Examples 2-4 and modified nylon 6 pellets wereobtained.

For the polymerization reaction, the modifiers were uniformly dissolvedin an aqueous lactam solution (85% aqueous solution). Microscopicobservation of cross-sections of the pellets produced indicated thatpellets prepared with the modifiers having the lower mole ratio ofethylene oxide in each of the pairs of addition products the nylon 6yarns prepared by blending modifiers which dissolved into the nylon 6(Controls 14, 15 and 16), and therefore they presented the sameproperties as the unmodified nylon 6.

On the other hand, those in which modifiers could not be dissolved intothe nylon 6 (Examples 12, 13, and 14) produced voids, (the diameters ofthe lateral cross sections thereof averaging 3n), which were long, inlinear form, and as a result, the ratios of strength of diffused light,lustre factors, and non-transparency characteristics of these yarns werehigh and they had a silkyl lustre and a dry touch.

Since the degree of extraction varies in accordance with the kind of themodifier used, the volume of voids produced by extraction may differeven though the proportion of blended modifier is the same. This ofcourse results in differences in optical properties.

In accordance with the present invention, more extractable modifiers(Examples 12, 13) are preferred to modifiers which are difiicult toextract (Example 14).

TABLE 7 Yarn Void after Ratio of breaka e Yarn-adhe- Solubility ofextracstrength Lustre Trans- Modifier (moles ethylene (brea Biresion ofmodifier in tlon(vol.l of scattered factor paroncy oxide per molesadduct) age/hour) irlngenee drawn yarn polymer percent) light (a)(percent) Control:

14 None 44x10 None 0 3.4 6.2 60 15 e-Caprolactam ethylene 0.1 43 10'...do Soluble 0 5.1 6.1 01

olxide addition product 0 Exampio12 e-Gaprolactam ethylene 0 nxur.....do Non-solublc-. 3.1 5.8 46 26 olrde addition product Control 16Lauryl alcohol ethylene 0.5 45x10 do Soluble 0 4.9 5.0 60

ogrlde addition product Example 18..... e-Caprolaotam ethylene 0.2 44X10-..-.do--...- Non-soluble 3.0 6.7 47 27 ((13310 addition product Control17 Nonyl phenol ethylene 1.0 4.4X- .....do-..-.. Soluble 0 5.0 6.1 59

oride addition product Example 14-.. Nonylphenoi ethylene 0.6 43X10-...-..do-.... Non-soluble 1.4 5.2 44 32 oxide addition product (40).

EXAMPLES 15-17 and then the tricot weaves were washed in a bath con-Hexamethylene diamine and adipic acid were reacted in accordance withconventional methods to prepare nylon 66 salt. This was dissolved in a55%, by weight, aqueous taining nonionic active agents for minutes atC., and for 30 minutes at 80 C. These tricot weaves then presented a dryand desirable touch and the waxy touch of unmodified nylon 66 waseliminated. Moreover, the

solution and then heated to 70 C. 25 dyed products were brilliantlycolored.

TABLE 8 Amount Void of after Ratio of modifier extraction strengthLustre w (v scattered factor Trans- Modifier percent) percent) light(UP) (a) parency Example 15 Laurtyl emine-EO-addition prod- 3.6 2.5 5.142 28 no 16 Pentaerythrlthol-EO-addition 3.6 2.4 5.1 40 28 product. 17Ethylene oxide-propylene oxide 4.0 3.1 5. 7 45 24 copolymer.

About 4 parts each of laurylamine ethylene oxide addition product mol ofethylene oxide per mol laurylamine), ethylene oxide addition product ofpentaerythritel (50 mol of ethylene oxide per mole pentaerythritol) anda 1:1 random copolymer of polyethylene oxide and polypropylene oxide(having an average of 5 monomeric units per molecule) were uniformlydissolved into separate quantities, consisting of 100 parts each, ofnylon 66 salt.

The respective monomer mixtures were then polymerized in autoclaves,while vigorously stirring the same, and then they were extruded intopellets.

The dispersed states of the modifiers in the pellets thus obtained werestudied and it was found that more than 70% by weight of the modifierswere dispersed finely in the form of spherical particles the averagediameter of which was less than 51.1..

The concentrations of oxyalkylene radicals contained in these polymerswere 0.8, 0.8 and 0.9 mmol/ gram polymer, respectively.

The modified nylon 66 pellets thus obtained were meltspun in the samemanner as in Examples 2-4, and the yarns were taken up at a speed of 900m./min. and then drawn at a drawing speed of 3,000 m./min.

Thus the drawn yarns whose birefringence were respectively 48 10- 47X l0and 48x10 (3 denier/ 6 filament) were obtained.

In regard to the melt-spinning states of the obtained yarns, therespective yarns had excellent melt-spinning states, and no yarnbreakage occurred. Further, no yarnadhesion of the drawn yarns wasobserved.

These yarns were extracted in the same manner and under the sameconditions as in Examples 2-4, and the optical properties were studiedwith the results thereof shown in Table 8.

All of these yarns had a silky lustre and nontransparency.

On the other hand, unextracted yarns were woven into tricot wa es inaccordance with conve t o al methods EXAMPLES 18-21 On ethylene oxideaddition product of e-caprolactam (50 mol ethylene oxide per molee-caprolactam) was phosphoric acid-esterified by using phosphoruspentoxide. The esterified addition product, neutralized with calciumhydroxide to produce metal salt, is referred to hereinafter as themodifier.

An aqueous solution was prepared by blending 5.2%, by weight, of thismodifier with e-caprolactam.

On the other hand, commercially distributed metakaolin (the refractiveindex of which is 1.60) was mixed along with a dispersing agent (sodiumpyrophosphate), and dispersed in water. After the metakaolin wasdeagglomerated, it was subjected to hydraulic elutriation and a slurrycontaining no metakaolin particles above 4,u, wherein the averagediameter of circles circumscribed about the particles was 1,, wasobtained.

This slurry was blended with the aqueous solution of e-caprolactamcontaining the above prepared modified in such a manner that apredetermined concentration of the slurry was obtained and then themixture was sufiiciently stirred, heated and polymerized. Extraction ofunpolymerized material were carried out in accordance with conventionalmethods and modified polycapramides containing 0.5% by weight and 1% byweight of metakaolin, and 4.8% by weight of modifier were obtained.

Other modified polycapramides, containing 0.5 and 1.0% by weight oftitanium oxide (the refractive index thereof being 2.52) and 4.8% byweight of modifier were obtained through hydraulic elutriation andpolymerization as described.

On the other hand, in accordance with the same polymerization method, amodified polycapramide containing 4.8% by weight of modifier alone, apolycapramide containing 0.5% by weight of metakaolin alone, and anunmodified polyamide, containing neither of them was obtained.

The above obtained polycapramides were melt-spun in accordance with thesame spinning method as in Examples 24, and the yarn products werecontinuously drawn to produce polycapramide fibers (40 denier/10filament) 22 mixture (dimer, trimer, and tetramer). Ethylene oxide wasadded to this polyamide oligomer mixture in accordance with conventionalmethods, (average mole ratio/ ethylene oxide per mol oligomer 50 mol)and an ethylthe birefringence of which was respectively 45 l- 5 oneoxide addition product (hereinafter referred to as the Now of the yarnshad irregular extrusion problems and modifier) was obtained. no yarnbreakage occurred during the drawin o eration. Commerciall distributedtalc (the refractive index g P Y They were excellently spun. thereofbeing 1.59) and kaolmite (the refractive index These drawn yams werewashed ith 60 C, h t water thereof being 1.56) were dispersed in waterwith a dispersand th n d ied, mg agent (sodium pyrophosphate). Hydraulicelutriation The reflecting property, touch, frictional property, and Wasused, In accordance With Stokes Principle, and an the amount of voidswere measured for each yarn and aqueous Slurry was Obtalned containingno coarse P the r lt th f are given i T bl 9 cles wherem the averagediameter of circles circumscribed The frequency of yarn breakage duringtricot warpabout the Particles the Slurry was ing i l shown i T bl 9Next, 6% by weight of the modifier was added to a These yarns weresubjected to tricot warping and setmonomer mPiture composed ofe'caprolactam and up in accordance with conventional methods. meFhYlened1ammnium ,adipflte (nylon 66 Salt) in a The difi d polyamide yamprepared by blending weight ratio of 85:15. This mixture was thencharged to fine white particles in an amount to satisfy Formula 3 an fas an 85% aquwus 501M191], and thermally (Examples 18-21) presented moreor less lower ratio of 20 polymenleq accordance convenuonal h Strengthof diffused light (U10) and lustre factor (a) The elutrlated slurrydescribed above of fine white parthan the modified polyamide yam(Example 21) prepared ticles (talc and kaol1n1te) was added in theamount shown by blending no fine white particles, but they all satisfiedm Table Whlle keepmg the reactlon temperature. at the Formulae 4 and 5,and silky lustre was obtained. 270 the pressure at 18 the Polymenzanon.In addition, the yarns had a remarkably low frictional 25 fi gig a 1 111 b d coefiicient between yarns, and the frequency of yarn 6 mo 1 ecope ymer my on P6 i h 0 tame breakage in the Warping process was verylow Gene? were washed by the same method described 1n Examples 24, andunreacted monomer was removed. iii-g g yams showed excellentprocessablhty charac- 5.8% by weight of modifier was dispersed in thepellets as fine spherical partlcles the average particle size ofbleggehien :g1:mg3?0:1vt2? itilfiierzlvl'ilgledgglrlgglii 17:21: 'liiesz e il ets were melt-s un in the same manner as mula 3 (Control 18),the frictional coefiicient was low. in Examplfes 1243 to produge drawnyam (70 denier/29 Processability of the yarn was excellent but the ratioof m t) the strength of diffused light (I/I was very 10W and l iigpinning state was excellent no yarn breakage at i ifi ifi gi z figiigggg gz g d the spinning nozzle or during the drawing operation was i wn a er e yarns a ob served been, sublected to ,i dIPPed Into 9 All ofthe modified polyamide yarns hadabirefringence refimng bath, containing2 g./l1tre of surface act ve agent of about 1 -3 and no yarmadhesion wasobserved. and 2 g./l1tre of sodium carbonate for 30 mlnutes to 40 Theseyarns were washed in the same manner as in extract the modlfiel and thensublected 9 l'efimng at Example 1, and a part of the modifier wasextracted. Then Tilereafiel the Y Was y and finlshedthe frictional andoptical properties of the yarns were Tricots obtained from the yarn ofthe present invention measured. presented a silky appearance and a drytouch. The modified polyamide yarns prepared by blending fine TABLE 9Difference of Frequency of refractive yarn breakage index between whentricot Amount Void after fine white Amount Ratio of warping is ofmodiextraction particles and of fine strength of Lustre Trans- Dynamiccarried out fier (wt. (vol. Kinds of fine polyamide white scatteredfactor parenc frictional (yarn breakpercent) percent) white particles(wt. percent) particles light (Illa) (a) (percent coefficient age/10 m.)

4.8 2.5 Metakaolin 0.07 0.5 4.5 38 30 0.61 0.2 4.8 2.5 o 0.07 1.0 4.3 352s 0. 56 0.1 2.2 2 f lgg ium oxide-.- 0. 99 0.5 2. g: 3.3g 2.:

4.8 2.5 Titanium oxide.-- 0.99 1.0 4.1 28 2A 0. 0.3 None 0 Metakaolim.0.07 0.5 4.1 812 52 0.62 0.2 None 0 None 3.2 7.1 57 0.80 7.2

EXAMPLES 22-23 60 white particles in amounts within the range of FormulaPolycapramide obtained by polymerizing e-caprolactam was extracted withhot water, and the extracted product 3 presented a silky lustre and avery low dynamic frictional coelficient.

TABLE 10 Difference of Void refractive Amount of Ratio of Amount ofafter exindex of fine fine white the strength modifier traction Finewhite partiparticles of scattered Lustre Trans- Dynamic wt. (vol. whitecles and wt. light factor parency friction percent) percent) particlespolyamide percent) (III.,) (or) (percent) coefficient was dried, and themonomer (e-caprolactam) contained therein was removed to produce apolyamide oligomer What is claimed is: 1. Method for producing polyamidefiber having improved silkyl lustre and silky touch comprising the stepsof (1) blending a melt spinnable polyamide with a polyalkylene ethermodifier which is substantially insoluble in said polyamide and hasexcellent thermal stability at the melting point of said polyamide, theproportion thereof, in millimol repeating alkylene oxide unit in saidmodifier per gram polyamide hereinafter referred to as a being in therange 3.5 to 0.2, (2) preparing from said blend modified polyamidepellets having said modifier finely dispersed therein as minuteparticles at least 50%, by weight, of which have an average axialdiameter in their cross-section of below 20 (3) melt-spinning saidmodifier polyamide pellets to prodce filaments, (4) continuously drawingsaid filaments until the birefringence, An, of said spun filaments isnot less than 49 log 32 wherein a stands for millimols (mmols) of therecurring alkyleneoxide unit in the polyalkylene ether modifiercontained in 1 gram (g.) of the polyamide; and (5) treating said drawnspun polyamide filaments with a selective solvent for said modifier saidpolyamide being substantially insoluble in said solvent, to producevoids in said filaments by the extraction of said modifier therefrom,said polyalkylene ether comprising an alkylene oxide adduct of amidoradical-containing compounds selected from the group consisting ofpolyamide oligomers and polyamide monomers, said adduct having anmolecular weight in the range from 600 to 60,000.

2. Method for producing polyamide fiber according to claim 1 whereinsaid filaments are drawn immediately after the melt spinning thereof andbefore being taken up.

3. Method for producing polyamide fiber according to claim 1 whereinsaid polyalkylene ether modifier comprises an alkylene oxide additionproduct, said alkylene oxide having from 2 to 3 carbon atoms.

4. Method for producing polyamide fiber according to claim 1 whereinsaid blending step comprises uniformly dissolving said modifier in apolyamide monomer or polyamide monomer solution and polymerizing saidmonomer and wherein said modifier particles in said pellets formedtherefrom have an average axial diameter in their crosssection of below5. Method for producing polyamide fiber according to claim 1 whereinfine white particles, having a refractive index of from 1.4 to 2.76 anda maximum diameter less than 10g and also less than the melt spunfilament diameter, are blended into said polyamide along with saidmodifier, said blend proportion being within the range defined by thefollowing formula:

(wherein C is the amount (wt. percent) of fine white particles; d is theabsolute value of the difference of refractive index between saidpolyamide and siad fine white particles).

6. Method according to claim 5 wherein said fine white particles areselected from the group consisting of talc, kaolinite, titanium oxideand calcium carbonate.

7. Method for producing polyamide fiber according to claim 1, whereinsaid solvent extraction of said polyamide filaments produces voidstherein totalting 0.5-13 volume percent of said filaments and theoptical property of a fiber comprised of said filaments has a ratio ofstrength of scattered light (I/I of from 1.5 to 15 and a lustre factor(a) of from 20 to 90.

8. A method as recited in claim 7, wherein said polyalkylene etheradduct is phosphoric acid-esterified.

9. A method, as recited in claim 1, wherein said polyalkylene ethermodifier has a molecular weight in the range from 1,000 to 20,000.

10. A method, as recited in claim 1, wherein said amidoradicalcontaining compound of said polyalkylene ether comprises ethylene orpropylene oxide addition products of tetragonal through tridecagonallactams.

References Cited UNITED STATES PATENTS 3,423,491 1/1969 McLain et al.264-49 3,551,538 12/1970 Yamamoto et al. 264-49 3,562,374 2/1971 Okamotoet al. 264-49 X 3,323,978 6/1967 Rasmussen 264-49 .UX 3,329,557 7/1967Magat et al. 264-49 UX 3,475,898 11/1969 Magat et al. 161-180 X3,314,919 4/1967 Most 260-37 NP X 3,405,211 10/1968 Cancio 264290 N XFOREIGN PATENTS 1,043,762 9/1966 Great Britain 264 DIG. 8

OTHER REFERENCES Miller, M. L., The Structure of Polymers, New York,Reinhold, c. 1966, pp. 566572 (Spe Polymer Science and Engineeringseries).

PHILIP E. ANDERSON, Primary Examiner US. Cl. X.R.

260-25 E, 2.5 M, 2.5 N, 37 NP, 37 AL, 78 S; 264-176 F, 210 F, 211, 290N, 344, DIG. 13, DIG. 61

